Torque measuring screw driver



Patented Oct. 21, 1947 UNITED STATES PTENT OFFICE TORQUE MEASURING SCREWDRIVER Hugh W. Bunting, Liberal, Kans.

Application October 21, 1944, Serial No. 559,765

1 Claim. 1

This invention relates to a tension screwdriver and it is primarily anobject of the invention to provide a tool of this kind whereby it ispossible to tighten screws all at the same tension with the advantage ofeliminating liability of springing and warping of the material withwhich the screws are employed.

A more specific object of the invention is to provide a tool of thiskind including a shank and an operating handle therefor and wherein saidhandle and shank are connected in a manner to allow relative turningmovement of the handle member and shank, whereby the twist of the shankwill determine the tension applied by the tool to the screw.

The invention consists in the details of construction and in thecombination and arrangement of the several parts of my improvedscrewdriver whereby certain important advantages are attained, as willbe hereinafter more fully set forth.

In order that my invention may be the better understood, I wil] nowproceed to describe the same with reference to the accompanyingdrawings, wherein:

Figure 1 is a view partly in elevation and partly in sectionillustrating a tension screwdriver constructed in accordance with anembodiment of the invention;

Figure 2 is a sectional view taken substantially on the line 22 ofFigure 1; and

Figure 3 is a sectional view taken substantially on the line 33 ofFigure 1.

In the embodiment of the invention as illustrated in the accompanyingdrawings, l denotes an elongated shank of spring steel having its outerextremity formed to provide a conventional blade 2 for usual engagementwith the head of a screw. The opposite end portion of the shank l iscontinued by an elongated flat bar 3 integral with the shank I anddisposed substantially diametrically thereacross.

The handle member 4 for the tool is tubular and has one end portion ofits bore 5 reduced, as at 6, to provide a cylindrical opening I throughwhich the inner portion of the shank l freely passes and which shank iscylindrical in form. The bar 3 is entirely housed within the handlemember 4 and extends alon the major portion of said handle member withthe outer end of the bar 3 rigidly connected by welding or otherwise asmay be desired to the rear or back head 8 of the handle member.

The opening I hereinbefore referred to is continued through a front head9 for the handle member and which head is welded to or otherwise maderigid with the handle and is circular in form with its outer face flat.In close contact with the outer flat face of the front head 9 is therear flat face of a cylindrical head I0 keyed, as at II, or otherwisefixedly secured to the rear portion of the shank l.

The heads 9 and I0 are of the same radii so that the peripheral facesthereof are flush. These peripheral faces of the heads 9 and i0 carrythe suitably spaced graduations [2 to provide ready reading to determinethe tension of the blade 2 upon a screw during a working operation.These graduations 12 are adapted to be read in connection with a properchart which is to be furnished with the tool.

It is believed to be readily apparent that during a working operation,there will be a tendency of the handle member 4 in its turning operationto twist the bar 3 and it is the extent of this twisting action whichdetermines the tension applied by the tool to the screw. The extent ofthis tension can be readily determined by the workman through the mediumof the graduations 12 hereinbefore referred to.

It is believed to be readily apparent that by the use of a tensionscrewdriver constructed in accordance with an embodiment of the presentinvention, it is possible to tighten a number of screws with the sametension so that liability of springing and warping the work iseliminated, together with the further liability of the screws breakingoff.

From the foregoing description it is thought to be obvious that atension screwdriver constructed in accordance With my invention isparticularly well adapted for use by reason of the convenience andfacility with which it may be assembled and operated.

What is claimed is:

A screwdriver of the character stated comprising a relatively longhollow handle closed at one end having a reduced axial opening throughthe other end, a screwdriver unit having a relatively long round shankformed at one end to provide 3 4 a blade, the other end of the shankextending through and turning freely in the said opening in REFERENCESCITED said handle, aflat torsion bar forming an integral The followingreferences are of record in the continuation of the said other end ofthe shank, file of this patent! said bar passing thru the hollow handleand 5 being secured to the said closed end of the handle, UNITED STATESPATENTS and a head mounted upon and secured to said Number Name Dateshank adjacent to the end of the handle through 1,686,714 Smith Oct. 9,1928 which the shank passes, and co-acting indicia 1,773,483 Guze Aug.19, 1930 upon the surface of the head and the surface 10 2,205,510Wolfram June 25, 1940 of the adjacent end of the handle. 2,394,022Storrie Feb. 5, 1946 HUGH W. BUNTING.

